1. Field of the Invention
The present invention relates to a compression spring formed of an elastic body made from a resin or rubber.
2. Description of Related Art
Compression springs of this type are known. One type of known compression spring includes an elastic body formed into a cylindrical shape, wherein a compression energy generated when the compression spring is pressed in the radial direction is absorbed by elastic deformation of the elastic body in the direction the elastic body is flattened.
For example, a compression spring shown in FIG. 9 of the present invention is disclosed in Japanese Patent (PCT international application) Laid-open No. Hei 7-502698, wherein a cylindrical main body comprises two cylindrical elastic bodies 01 and 02 stacked in the radial direction. A connecting portion 03 is formed into a neck-shape between the two cylindrical elastic bodies. Furthermore, a flat top plate 04 and a flat bottom plate 05 are provided on the two cylindrical bodies 01 and 02, respectively.
The top plate 04, the bottom plate 05 and the connecting portion 03 respectively have circular holes 04a, 05a and 03a through which a bolt co-axially passes.
Compression energy generated when the compression spring is pressed in the radial direction is absorbed by elastic deformation of the cylindrical elastic bodies 01 and 02 in the direction the elastic bodies 01 and 02 are flattened.
The above compression spring is used in a state in which a bolt passes through the circular holes 04a, 05a and 03a respectively formed in the top plate 04, bottom plate 05 and connecting portion 03 for stabilizing the shape of the compression spring when the compression spring is deformed. In other words, if the compressing spring is not supported by the above bolt, the cylindrical main body may be bent at the necked connecting portion 03, resulting in it being difficult to ensure a specific load-deformation characteristic of the compression spring because of instability of the shape upon deformation.
In this way, the related art compression spring cannot stably absorb a compression energy unless it is supported by a supporting member such as a bolt. The related art compression spring which requires such a supporting member limits the versatility of the compression spring.